Electrode holder for spark ignited oil burners



Oct. 8, 1968 I J. CHAPPUY 4 3,404,940

ELECTRODE HOLDER FOR SPARK IGNITED OIL BURNERS Filed March 22, 1966 A INVENTOR JEAN, cHaPPu'Y 1D) /)"ZW8ZWM W I 3,404,940 Patented Oct. 8, 1968.

Uni ed St t s e om 3,404,940 :f ELECTRODEHOLDER FOR SPARK IGNITED I r .orL BURNERS JeauChappuy, 6 Ave. des Pavillons, Colombe's,

. 'Hauts-de'-Seine,Fr'ance w 1' v Filed Mar. 22,1966, Ser. Nix-536,396

Claims priority, applicaaiolgzl rance, Mar. 26, 1965,

to be-fixed on an appropriate support element, such as the nozzle adapter or. the oil supply tube of an oil burner, and to mount the known type of sleeves carrying the electrodesproper. j.

Yet another object of the invention is to provide an electrode holder of the type mentioned in which vfixing of ignition device foroil burners including body of 7 I thermoplastic or ,thermosetting material carrying the two electrodes for providingan ignition spark adjacent the nozzle of. the oil burner. This body is fonmed with an aperture receiving a component of the oil burner, such as,

for example, anozzle adapter. The external surface of the adapter and the aperture in the body are so formed as to prevent relative angular displacement of. thebody with respect to the oil burner component, while providing for axial movement of the body relative to the component of the oil burner. Pressureexerti ng means are provided for assuring a tight-conforming fit between the bodyancl the component part of the oil burner, preventing relative angular displacement of these twov parts.

This invention relates to ignition devices foroil burners and,- more particularly, to a novel and improved holder for the sparking electrodes used to ignite oilasprayed from an .oil burner nozzle.

It is known to ignite oil. burners, for example, those I burning residualoils, by aflashing sparkatawoltage of about 8,000 to 15,000 volts between electrodes provided for this purpose- These electrodes are-mounted in a member called an.electrode holder,- fixed on an appro priate element of the burner.-For example, such element could be the nozzle adapter of the burner. -A nozzle adapter is generally-machinedfrom brass and is threaded or soldered to the end of the oil supply .tube and carries, at its free end, an oil, atomizing nozzle. p

In known constructions, these electrode holders comprise a metal body-fixed on the adapter, and formed with two parallel bores receiving the isolating shields, of ceramic material, in which are mounted the hollow pinsof the electrode holder on its support is assuredbythe pressure produced by elastic deformation of the electrode holder body'resulting from its mounting on the support element.

A further object of the invention is to provide an electrode holder in which the elastic pressure of the body of the holder on the support element is sufiicient to retain a desired longitudinal position while permitting displacement of the body slidably along its support element by the application of a suitable force.

Still another object of the invention is to provide an electrode holder of the type mentioned and which has a conforming fit with the support surface which is formed to prevent rotation of the electrode holder body on its support.

Still a further object of the invention is to provide an electrode holder of the type mentioned in which the body of the-holder is mounted on its support with the help of a groove cooperating witha conforming surface of the soft steel carrying the electrodesproper.-The electrodes An object of the present invention is to avoid the disadvantages of prior art electrode holders. I

Another object of the invention is to provide an electrodeholder comprising a body' molded from insulating material of either a thermoplastic or thermosetting nature a and preferably possessing a certain elasticity.

' support element and having a small play therewith, the

elastic pressure being produced by a projection oriented to press toward theinterior of the groove upon engagement of the body of the electrode holder on its support element.

Still another object of the invention isto provide such I an arrangement in which the projection is preceded by a ramp facilitating engagement of the electrode of the electrode holder with its support element and assuring a progressively increasing elastic pressure.

A further object of the invention is to provide an electrode holder of the type mentioned in which the sleeves carrying the electrodes proper are imbedded in the body of the electrode holder during molding of the Yet another object of the invention is to provide an electrode holder of the type mentioned andwhich is formed as a one-piece unit integral with the nozzle adapter.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings.

' In the drawings:

FIG. 1 is a front elevation view of an electrode holder embodying the invention; F FIG. 2 is a side elevation view of the electrode holder; FIG. 3 is a side elevation view of the electrode holder of FIGS. 1 and 2 as mounted on a nozzle adapter of an oil burner; and I I FIG. 4 is a view similar to FIG. 3 but showing a variation in which the electrode holder is mounted on the oil supply tube of the oil burner.

In the embodiment of the invention shown in FIGS. 1 and 3, the body of the electrode holder l is molded from a thermoplastic or thermos'ett ing dielectric synthetic resin material, forexample, thatknoWn'under-the nameof Rilsan. The body 1 mounts two cylindrical electrodes 2 of soft steel. Each electrode carries coaxially thereof, at one of its extremities, a silicon steel pin 3 having a diameter less than the electrode 2. The exterior parts 4 of the pins 3 are finally bent manually to regulate the spacing and the positioning of the electrode points 5. These pins extend through an axial cylindrical passage in the associated electrode 2 and are maintained therein by the pressure due to preliminary deformation of the pins to provide projections in a zone thereof which is at the longitudinal center of the passage when the pins are inserted-therein. This deformation deforms the soft steel of the electrode'sleeve by metal flow to form two diametrically opposite projections 6 which form lateral projections engaging in the electrode holder.

A thread 7, either 5.1. or I.S.O., is formed. on the other end of each electrode 2 and provides for fixing thereto a connection (not shown) for feeding the high voltage electric current, produced by an ignition transformer, to the electrodes.

The process of producing each electrode is known per se. The lateral projections 6 extending diametrically of each electrode 2 prevent rotational or translatory movement of the latter when the plastic material of the body of the electrode holder 1 is poured, and during its hardening, around the electrodes 2 which have been previously positioned in a suitable mold.

The length and the position of the electrodes is a function of the usual regulation of the spark ignition, under high voltage, of an atomized oil jet discharged from the nozzle.

All modifications of dimensions, of position, and of spacing of electrodes are possible and are within the scope of the invention.

The positioning of the thus formed electrode holder on the nozzle adapter A is then effected, the adapter A being of a known type and having the dimensions and the form required by the usual international specifications.

The adapter has a cylindrical external surface along part of its length, usually formed by machining a bar of polygonal, such as hexagonal, cross section. The cylindrical part represents about two-thirds of the total length of the adapter, and the rest of the external surface of the adapter is constituted by the six side faces of the bar;

L 2" I 2: th plastic material used, and the assembly tolerances,

- permit the necessary slight-deformations toeffect a frictional drag between the two pieces, without interfering with the sliding friction, easily performed by hand. The height of the projection 10 will, be determined to provide the correct pressure between the two pieces.

In the modification shown in FIG. 4, the electrode holder can be fixed in the same manner on the oil feed tube rather than on the nozzle adapter. Hexagonal bore 8, in FIG. 4, is replaced by a cylindrical bore 14 having a diameter corresponding to;the diameter of the oil feed tube 15. Positioning is effected by virtue of sliding the two parts relatively, radially and axially of the tube, and the fixed position is set by means ofa set screw or the like 16.

Ele'c'trodeholdersinac 'cordance' with the invention have many advantages in comparison with known electrode'holders. Thus, they are less expensivebecause the number of parts has been reduced to the body,of dielectrict material and the electrodes. The electrodes ,arefixed in the body of the holder during molding of the latter and without the necessity of providing the separate means for holding the electrodes in the body. The fixed positioning of the body of the-electrode holder on its support element is automatically assured by elastic deformation occurring during mounting of the body 'of its support element without the necessity for using-separate 'fixing means such as screws or similar'elements. Furthermore, the-electrode holder is easilyadjusted by' sliding, on its support element, in addition to the electrode holder having a strong construction. The electrode holder is easy to fabricate inasmuch as it is-molded,=and it presents a reduced incumberance.'

-It should-be especially noted that'the electrode holder can be manufactured as a single piecewith the adapter and secured with the latter to the oil feed tube;

While specific embodiments of the invention have been shown and described in detail to illustrate the ap- The electrode holder 1 is formed, along an axis parallel I to the axes of electrodes 2, with a hexagonal aperture 8 whose dimensions are slightly in excess of the dimensions of the'hexagonal part of the nozzle adapter A. The assembly tolerances provided to the order of tenths of a millimeter are compatible with a correct fixing of the, two

pieces one on the other. The coincidence of the hexagonal bore 8 with the hexagonal exterior surface of adapter A provides for positioning of the electrode holder in a fixed radial relation on the adapter A, preventing rotation of the electrode holder.

' In order to provide an axially fixed positioning of the electrode holder 1.0n the nozzle adapter, the interior surface 9 of the hexagonal bore 8 is formed, along an axis tangent to the middle of this face and parallel to the axes of the electrodes, with a projection 10 whose right section is approximately that of a semi-circle. This bulge or projection 10 is formed by molding at the same time as the electrode holder is molded.

In order to permit the mounting of the electrode holder 1 on the hexagonal part of adapter A, the projection 10 includes, at one of its ends, an inclined plane 11. The frictional engagement of the holder on the adapter is etfected in the following manner. The projection 10, upon mounting of .the electrode holder on the adapter, deforms the lateral face 9 of bore 8 from which it projects, and thus induces a lateral pressure on the other faces of the, hexagonal bore 8, suchas the faces 12 and 13, against the corresponding surfaces of adapter AjThe elasticity of plication of the principles-of the-invention, it will be understood that the invention may beembodied otherwise without departing from such principles.

What is claimed is:

1. An electrode assembly, for the high voltage spark ignition of an oil burner having projecting ignition electrodes andincluding, as components, an oil supply tube and a nozzle adapter mounted on the supply tube, said electrode assembly comprising a relatively elastic molded body of dielectric synthetic resin material constructed to receive "sleeves carrying the projecting electrodes; said body being constructed for fixed mounting on. a compo nent-of the oil-burner through its inherent-elasticity; said body beingformed with an aperture having-a contour conforming tothat of the component on which .it is mounted, ina manner such as to restrain relative angular displacement of said body on its mounting component; said body having tightening means thereon projecting into the interior of said aperture to engage-the body mounting component to tighten the bodyon its mounting component by elastic deformation of the body, and providing for sliding of said bodyon itssupport component in adirection extending axially of the latter. 2. An electrode assembly, as claimed in claim 1, i

' which said elasticity provides a pressure,.when said body is mounted on its component, maintaining said body substantially fixed in position against angular displacement on its mountingcomponent. v

3..An electrode assembly, as. claimed in claim 2,. in which the elastic pressure exerted between said body and its component has a value sufl'icient to retain thebody fixed longitudinally on its component while providing for longitudinal displacement of the bodyv by sliding along its mounting component under a force of a preselected value.

4. An el ctrode assembly, as claimed 'in*claim 2, in

which'th'e elastic pressure is produced by' a pressure projection integral with said body and extending toward the interior of said aperture, upon engagement of said body with its support component.

5. An electrode assembly, as claimed in claim 4, including a ramp sloping away from said projection and facilitating engagement of said body on its support component while assuring a progressively increasing pressure.

6. An electrode assembly, as claimed in claim 1, in which the material of said body is selected from the class consisting of thermoplastic and thermosetting synthetic resins possessing elasticity in the formed state.

7. An electrode assembly, as claimed in claim 1, in which the component mounting said body has a polygonal cross section, and said aperture has a polygonal cross section conforming to that of the mounting component.

6 References Cited UNITED STATES PATENTS 957,951 5/1910 H-aase 31796 977,521 12/1910 Goldblatt 31796 1,010,897 12/1911 Grinnell 317-96 1,139,759 5/1915 Fox 317-96 3,154,281 10/1964 Frank 24s-201 FOREIGN PATENTS 560,916 4/1957 Italy. 792,266 3/1958 Great Britain.

' BERNARD A. GILHEANY, Primary Examiner.

VOLODYMYR Y. MAYEWSKY, Assistant Examiner. 

